Container closure



Patented July 19, 1949 2,410,027 cox'rsmnn CLOSURE John G. Rots, Jr;

Railway, N. 1., assignor to Sun Chemical Corporation, New York, N. Y., a corporatlon of Delaware No Drawing. Application April 6, 1948,

Serial No. 19,441

Claims. (Cl. 111-76) This invention relates to coated liners for use as facing material, and which are particularly useful as a component of crown caps, screw caps and similar closures and as a facing material for the inside of paper containers.

One object of the present invention is to provide a coated paper liner which is resistant to objectionable change or deterioration in contact with liquids and vapors of materials normally packaged in closures. 1

Linings for container closures, to be completely efl'ective, must be of such nature that they are resistant to attack by, or discoloration from, contact or exposure to the liquid material or the vapor of the liquid material which is present in the closure. Also, the lining material must be of such nature that it will conform to the shape and irregularities of the container at the surface where the lining is in contact with such container, to provide a satisfactory seal .and to pre- 2 factory materials for utilization in providing such continuous layer include resins such as polymerized vinyl halides, polymerized vinylidene halides, resins which contain between 40 and 95 percent by weight of polymerized vinyl or vinylidene halides, either admixed with or as interpolymers with vinyl esters, acrylic acid, esters of acrylic acid, 'acrylonitrile and alkyl substituted acrylic acids and their esters. Such resinous materials satisfactorily can provide substantially all of the continuous layer which is present on the base material as the first coating thereon. Also, such resinous materials as those above described may be admixed with plasticizers and resins such as maleic anhydride glycerol esters of rosin'or the tripolymer resin made from maleic anhydride,

. vinyl halide and vinyl acetate. Such material vent escape of the liquid or vapor from the container.

Since materials which are normally placed in containers such as bottles, cans, and the like, include a great variety of diflerent classes of compounds, the lining material must be resistant to attack by, or discoloration from, a great number of different kinds of compounds, for example, such diverse materials as sodium hydroxide, ammonia, sodium hypochlorite solution (such as commercial bleaches). phosphoric acid, hydrochloric acid, acetic acid, alcohols, mineral oils, witch hazel, cotton seed oil, essential oils, solvents such as ketones, and disinfectant solutions and the like, among others.

I have found, according to the present invention, that liners for container closures which are resistant to objectionable attack or discoloration from liquids and vapors or vapor materials, such as those described above, can be prepared by providing a base material such as a paper base on which there are coated successive layers of particular materials.

In preparing a lining of the present invention a base such as a paper base first is coated with a continuous layer of a resinous material which contains as a constituent thereof 80 to 100 per cent of a. vinyl or vinylidene resin, or a mixture or copolymer of such resin with additional resinous material and plasticizer. For example, satismay be used in amounts up to 20 per cent of such coating.

One satisfactory way of preparing such layer of resinous material upon the paper base consists in applying to the paper base an aqueous emulsion or dispersion of the resin or mixture of resins, and thereafter drying the coated paper to remove therefrom the liquid material. Instead of applying the coating from aqueous admixture solutions of the resinous material may be employed. I

In practice it is desirable to put on a coating which is approximately .0075 inch mil.) in thickness. satisfactorily, such application may be effected by means of commercial coating operations such as by the use of thewell-known knife coating machines, roller coating machines, reverse roller coating machines, or by the process known as the dip and squeeze process, wherein the base material is impregnated in a bath of the desired mixture or solution and excess material subsequently removed by squeezing operation accomplished by passing the base material through a set of squeeze rollers set to remove a desired amount of material. After application, as above described, the coated base material is satisfactorily dried at temperatures up to 280 F. to remove the liquid material.

Such a coating is impervious to water and is satisfactory for very limited uses. Because of the nature of the resinous materials, the product lining material has thereon a coating which is soluble and is swollen by solvents such as methyl ethyl ketone, benzene. and the like, which is attacked by and softened in the presence of essential oils and which is discolored by contact with alkali. For these reasons a lining containing only such resinous materials will have limited application.

To provide a lining which is completely resistant and which has a much wider ran e of application and utility, there is provided, according to the present invention, a top coat which is applied to the above described material to produce a lining which has the desired properties of having resistance to attack and/or discoloration from contact with liquids or the vapors or the liquids such as those above described. Particularly satisfactory for utilization as such top coat material is polyethylene. a solid resinous material secured by polymerization of ethylene at temperatures between 100 and 300 C. and under pressure up to 1200 atmosphe Because oi. its almost complete inertness and insolubility in most solvent materials, polyethylene is extremely diiilcult to apply as a coating material. This is the result or its insolubility and because the coating ordinarily has very poor propertles of adhesion and, will not remain tightly bound upon surfaces to which it is applied. I have found. according to the present invention, that such difliculties may be overcome and a satisfactory bonding of the polyethylene top coat to the first coating secured by utilization together with the polyethylene of a hutylatedurea-formaldehyde resin. Such resinous materials are secured by interaction of urea, formaldehyde and butanol to provide a condensed material which is soluble in alcohols and which also has the property of further hardening under heat to provide a thermoset resin. One material which has been utilized which is satisfactory contains 60 per cent solids dissolved in a mixture of 60 per cent butanol and 40 per cntxylol. A-satisfactory admixture for preparing a top coat or the present invention is secured by dissolving polyethylene in xylol to give an admixture containing 15 per cent solids. This admixture is heated to approximately 180 F. in order to secure a satisfactory solution, and there is added thereto an amount of butylated urea-formaldehyde resin in solution as above described to yield approximately parts by weight of butylated urea-formaldehyde resin for each 90 parts by weight of polyethylene resin.

Such admixture is applied as a coating to a base material such as paper containing a continuous layer of resinous material such as those set forth above by coating operations such as the knife coating or roller coating above described to provide a layer having a thickness of approximately mil. After application or coating, the coated material satisfactorily is baked for a period of 20-25 minutes at temperatures of the order of 275 F. Such composite liner is resistant to attack by or discoloration from materials such as those set forth above which are ordinarily packaged in containers and for which lining closures are desirable. The combination of coating provides resistance to both the liquids and the vapors of the liquids and is unaffected even upon long standing in contact with such materials.

Examples of satisfactory formulations for the continuous coat layer first applied to the base material includes the following compositions, which are prepared and utilized as dispersions.

Parts by weight Vinylidene chloride-acrylonitrile copolymer resin Dibutyl phthalate 8 Water 46 Vinyl chloride-vinyl acetate copolymer resin- 42 Dioctyl phthalate 18 Water 46 Vinyl chloride-vinyl acetate copolymer resin- Malelc anhydride glycerol rosin ester resin 15 Water a 55 Vinyl chloride-vinyl acetate copolymer resin- 50 Tripolymer resin from maleic anhydride,

vinyl halide and vinyl acetate 4 Water 46 While the above described product and processes of making the same constitute prererred embodiments of the invention, changes may be made therein without departing from the scope of the invention, as defined in the appended claims.

What is claimed is:

1. A lining for container closures, comprising a paper base and a coating thereon comprising a continuous layer consisting of 80 to 100 per cent by weight or resinous material selected from the group consisting'ot polymerized vinyl and vinylidene halides and resins containingeo to 95 per cent by weight of vinyl and vlnylidene halides as mixed and interpolymers with vinyl esters, acrylic acid, esters of acrylic acid, acrylonitrile and alkylsubstltuted acrylic acids and their esters, the remainder of said continuous layer being a material selected from the group comisting of esters of phthalic acid, maleic anhydride glycerol esters of rosin and a tripolymer resin made from maleic anhydride, vinyl halide and vinyl acetate, and a continuous top coating comprising polyethylene and a butylated urea-formaldehyde resinous material.

2. A lining for container closures, comprising a paper base and a coating thereon comprising a continuous layer of an interpolymer or vinylidene halide and acrylonitrile, and a continuous top coating comprising polyethylene and a butylated urea-formaldehyde resinous material.

3. A lining for container closures, comprising a paper base and a coating thereon comprising a continuous layer of an interpolymer of vinyl chloride and vinyl acetate, and a continuous top coating comprising polyethylene and a butylated urea- !ormaldehyde resinous material.

4. A lining for container closures, comprising a paper base and a coating thereon comprising a continuous layer consisting of to per cent by weight of an interpolymer of vinylidene halide and acrylonitrile, the remainder of said continuous layer being dibutyl phthalate, and a continuous top coating comprising polyethylene and a butylated urea-formaldehyde resinous material.

5. The process of forming linings for container closures which comprises the steps of coating a paper base with a continuous layer consisting of 7 80 to 100 per cent by weight of resinous material hydride glycerol esters of rosin and a tripolymer resin made from maleic anhydride, vinyl halide and vinyl acetate, and thereafter applying a continuous top coating comprising polyethylene and a butylated urea-formaldehyde resinous material, and thereafter heating said coated material. JOHN G. ROTE, JR.

No references cited 

